From European Patent Reference EP-A1-O 567 805, a hydraulic piston engine is known, which has a number of axial cylinders. The cylinders are circumferentially arranged in a rotatable cylinder barrel.
Each of the cylinders is provided with a channel, which alternatingly communicates with an inlet port or an outlet port in a housing. It is apparent that the engine is provided with synchronizing means of the type of tooth gear transmission. This type of synchronizing means has backlash which in connection with prior art engines may cause noise, vibrations and power losses. The drawings show a longitudinal cross sectional view showing that the pistons and cylinders in the cylinder barrel are not positioned diametrically opposite to each other. Prior known hydraulic rotating axial piston engines, having synchronizing means with backlash, are namely provided with an uneven number of pistons and cylinders.
From U.S. Pat. No. 4,920,860 a hydraulic piston engine is known having synchronizing means of the type universal joint of tripoid synchronization. From the cross sectional view of the drawing it is apparent that the pistons and cylinders in the cylinder barrel are not arranged in diametrically opposite positions. From the description it is apparent that the number of cylinders is nine, i.e., an uneven number of cylinders. This type of synchronization also has backlash, which in combination with the present type of engine causes noise and vibrations.
It is believed that the common reason behind the above described disadvantages with prior known axial hydraulic piston engines is that the synchronizing torque changes direction.
The object of the present invention is to provide a hydraulic rotating axial piston engine having reduced noise level and reduced vibrations.
The present object is obtained by means of an engine which is characterized in the combination that the cylinders and pistons are an even number and are positioned pairwise diametrically opposite to each other, and that synchronizing means is provided having a synchronizing torque, which during the entire rotation of the cylinder barrel is directed in substantially one single direction. The ports of the housing and the cylinder barrel ports are arranged to substantially simultaneously discharge and pressurize the pistons in diametrically opposite cylinders.
The present invention relates to a hydraulic rotating axial piston engine. The engine has a housing, enclosing a rotatable cylinder barrel. The barrel has a number of axial cylinders with a number of reciprocating pistons. The pistons reciprocate between two defined end positions, and cooperate by means of piston rods with spherical recesses in an angled plate in order to obtain the reciprocating movement. The pistons are inclined relative to the longitudinal axis of the cylinders, and the cylinders have ports alternatingly acting as inlet and outlet ports. The housing has at least one inlet and outlet channel, each with a kidney shaped port, facing towards the inlet and outlet ports of the cylinder barrel. The kidney shaped ports communicate with a number of the ports at the barrel.
The cylinder barrel is rotatable relative to a first axis, which is inclined relative to a second axis of an input/output shaft. The angled plate is rotatable together with the input/output shaft around the second axis. The cooperation between the piston rods and the recesses in the angled plate create a driving torque in the angled plate. The rotation of the cylinder barrel and the angled plate is synchronized by means of synchronizing means, which includes synchronizing torque transferring surfaces having backlash.